November 2017 cnn; Tens of millions more Americans now have high blood pressure. Almost half of all Americans — 46% — are now considered to be in the high blood pressure category based on new guidelines released Monday.

High blood pressure should be treated at 130/80 rather than 140/90, according to the new parameters set forth by the American Heart Association, the American College of Cardiology and nine other health professional organizations.

Practicing physicians and the public are “going to be a little bit shocked or taken aback by a diagnosis of Stage 1 hypertension with a blood pressure of 130/80, which historically has been considered a normal, well-controlled blood pressure,” said Dr. William White, a professor in the cardiology center at the University of Connecticut School of Medicine.

“That will involve 50% of men and 38% of all adult women in the US,” estimated White, who was not involved in writing the guidelines. “So it’s a huge number of people.”

One in three Americans had previously been diagnosed with the condition, but now 14% more Americans will be diagnosed with high blood pressure. The new guidelines will classify 103.3 million people as having high blood pressure, while the previous guidelines placed only 72.2 million Americans in this category, according to the authors of the report.

White added that there might also be some confusion on doctors’ part about how they should advise patients, because the new treatment guidelines are “an enormous document.”

Although all patients will be counseled about lifestyle changes, such as exercise, only a small fraction will be prescribed medication, according to the authors. This includes “watching your salt, exercising more regularly, relaxing, getting a proper amount of sleep, eating a little more potassium-rich fruits and vegetables,” White explained.

Hypertension or high blood pressure is second only to smoking for causing preventable heart disease and stroke deaths, the authors said.

What are the guidelines?

The new guidelines define normal as less than 120/80. When systolic pressure (the first number) is between 130 and 139 or diastolic (the second number) is between 80 and 89, this will be referred to as Stage 1 hypertension. Stage 2 is when systolic is at least 140 or diastolic is at least 90.

Hypertensive crisis is when the top number rises above 180 and/or the bottom number is over 120. At this point, patients will require prompt changes in medication or immediate hospitalization if there are signs of organ damage.

The new guidelines eliminate the category of prehypertension, which was used for systolic readings between 120 and 139 or diastolic numbers between 80 and 89.

The recommendations also expand the use and frequency of out-of-office blood pressure monitoring for greater accuracy. According to White, there is “a fairly substantial rate of blood pressure variability in doctor’s offices from one day to the next, from one week to the next.”

“It’s actually not the most robust measurement,” he said. “We are sometimes totally shocked when we put a 24-hour blood pressure monitor on a patient, by what the differences are compared to normal activities in normal life compared to what it can be in doctors’ office. It can be drastic.”

He has seen people who register 166/80 in the doctor’s office but 128/70 when measured over the course of a day. “If that person got treated based on the doctor’s office blood pressure alone, they would be grossly overtreated,” White said.

The authors, who include a panel of 21 scientists who reviewed more than 900 studies, believe the impact of their new guidelines will be greatest among younger and middle-age adults, with prevalence of high blood pressure expected to triple among men under 45 and double among women under 45.

Drugs will now be recommended for patients with related health problems coupled with high blood pressure, as defined by the new guidelines.

“This will cause the greatest amount of controversy with physicians,” White said, explaining the new rules take what doctors thought all their lives was a “normal blood pressure” and treating it with drugs.

“I am a practicing doctor,” he added. “Patients are going to say ‘I don’t want to do that. I want to try losing weight first. I want to try, you know, doing more exercise.’

“It’s going to be a really tough challenge to follow these guidelines in reality,” he said.

Dr. Tom Frieden, president and CEO of the Resolve to Save Lives campaign, said that “the new guidelines clearly state treatment with medicine should begin if a patient reaches 140/90, an important piece of clarity in an area that has experienced much debate.” Frieden, former director of the US Centers for Disease Control and Prevention, was not involved in the new guidelines.

“The drugs approved to treat high blood pressure are all generic. For just a few dollars a day, you can save millions of lives,” he said.

Worldwide, as well as in the US, high blood pressure is “sorely undertreated,” Frieden said. “This is unacceptable, and we’re committed to seeing this change.”